Process recipe modification in an integrated circuit fabrication apparatus

ABSTRACT

One embodiment of the present invention is a method for modifying process recipe information utilized by a wafer processing system having a controller with permanent rewritable storage, memory, a first and a second communication interface, and a user interface; and one or more process cells to process a wafer; which method comprises steps of: (a) storing baseline process recipe information in permanent rewritable storage; (b) retrieving baseline process recipe information from permanent rewritable storage for a wafer in a group of wafers to be processed and storing it in memory; (c) receiving process recipe modification information utilizing the second communication interface and storing the process recipe modification information in memory; (d) overwriting at least portions of the baseline recipe information in memory with the process recipe modification information to form new recipe information; and (e) processing the wafer utilizing the new recipe information.

TECHNICAL FIELD OF THE INVENTION

[0001] One or more embodiments of the present invention pertain tomethod and apparatus to modify process recipes in apparatus utilized,for example, and without limitation, to fabricate integrated circuit(“IC”) devices.

BACKGROUND OF THE INVENTION

[0002]FIG. 1 is a pictorial representation of prior art wafer processingsystem 100 that is utilized to fabricate integrated circuit (“IC”)devices. As shown in FIG. 1, wafer processing system 100 comprises oneor more process cells 103-105, wafer transfer system 121, and factoryinterface 122. Each of process cells 103-105 is configured to perform aprocess on a wafer such as, for example, and without limitation, achemical vapor deposition (CVD) process, a physical vapor deposition(PVD) process, an electro-chemical plating (ECP) process, and so forth.Factory interface 122 includes cassette loadlock 123. Cassette loadlock123 stores one or more wafer cassettes, and individual wafers are movedfrom cassette loadlock 123 to process cells 103-105 by wafer transfersystem 121. Further, the functions performed by wafer processing system100, and the order in which these functions are performed, arecontrolled by tool controller 200. Tool controller 200 is connected toeach of the above-described system components in a manner that is wellknown to those of ordinary skill in the art to provide data andinstructions thereto, and to receive data therefrom. In particular, withrespect to process cells 103-105, at least a portion of the data andinstructions provided thereto includes information that is referred toherein as “process recipe information” or process recipes or recipes. Asis well known to those of ordinary skill in the art, a recipe specifies,among other things, timing, duration, and sequences of events that takeplace in a processing cell. As such, a recipe may be utilized, forexample, to activate gas valves to enable gases to enter a process cell,to set ratings for heaters to enable process temperatures to be set, toset ratings for pumps to enable process pressures to be set, and soforth.

[0003] As is well known, wafer processing systems like that shown inFIG. 1 are designed to provide substantially similar processing results(i.e., within predetermined manufacturing tolerances) for as long aspossible. Further, as dimensions used to fabricate IC devices becomesmaller, manufacturing tolerances are becoming smaller and deviationsfrom such tolerances are becoming more costly. As such, there is asubstantial benefit in discovering processing results that exceed thepredetermined manufacturing tolerances. The benefit accrues when, forexample, a process cell that is producing poor processing results isidentified and removed from service. This is advantageous because asource of defective IC devices is removed from service in the factory,and waste is reduced.

[0004] However, it has been determined that additional benefits can behad by studying processing results, and identifying a tendency of aprocess cell to produce processing results that (while being withinmanufacturing tolerance limits) are approaching tolerance limits.Further, it has been determined that such additional benefits can beobtained in such instances by taking two types of actions. The firsttype of action is to modify processing recipes of downstream waferprocessing systems to compensate for processing results produced by anidentified process cell. The second type of action is to modifyprocessing recipes of the identified process cell to cause itsprocessing results to be closer to a center of the tolerance limitrange. These actions provide still further benefits in that they mayprolong the time before processing cells have to be taken out of servicefor maintenance.

[0005] In light of the above, there is a need for method and apparatusto enable such new or modified recipes to be transmitted to and used by,wafer processing systems.

SUMMARY OF THE INVENTION

[0006] One or more embodiments of the present invention advantageouslysatisfy the above-identified need. In particular, one embodiment of thepresent invention is a method for modifying process recipe informationutilized by a wafer processing system having a controller with permanentrewritable storage, memory, a first and a second communicationinterface, and a user interface; and one or more process cells toprocess a wafer; which method comprises steps of: (a) storing baselineprocess recipe information in permanent rewritable storage; (b)retrieving baseline process recipe information from permanent rewritablestorage for a wafer in a group of wafers to be processed and storing itin memory; (c) receiving process recipe modification informationutilizing the second communication interface and storing the processrecipe modification information in memory; (d) overwriting at leastportions of the baseline recipe information in memory with the processrecipe modification information to form new recipe information; and (e)processing the wafer utilizing the new recipe information.

BRIEF DESCRIPTION OF THE FIGURE

[0007]FIG. 1 is a pictorial representation of a wafer processing systemthat is utilized to fabricate integrated circuit (“IC”) devices;

[0008]FIG. 2 is a pictorial representation of the wafer processingsystem shown in FIG. 1 used in conjunction with a module controllersystem in accordance with one or more embodiments of the presentinvention.

DETAILED DESCRIPTION

[0009]FIG. 2 is a pictorial representation of wafer processing system500 that is used in conjunction with module controller system 400 inaccordance with one or more embodiments of the present invention. Inaccordance with one or more embodiments of the present invention, waferprocessing system 500 is like wafer processing system 100 shown in FIG.1 in that it comprises one or more process cells 1103-1105, wafertransfer system 1121, and factory interface 1122, wherein: (a) each ofprocess cells 1103-1105 is configured to perform a process on a wafersuch as, for example, and without limitation, a chemical vapordeposition (CVD) process, a physical vapor deposition (PVD) process, anelectro-chemical plating (ECP) process, and so forth; (b) factoryinterface 1122 includes cassette loadlock 1123 (cassette loadlock 1123stores one or more wafer cassettes, and individual wafers are moved fromcassette loadlock 1123 to process cells 1103-1105 by wafer transfersystem 1121); and (c) the functions performed by wafer processing system500, and the order in which these functions are performed, arecontrolled by tool controller 1200. However, wafer processing system 500is different from wafer processing system 100 shown in FIG. 1 in that:(a) wafer processing system 500 further includesmetrology/inspection/review cell 1124 that comprises one or moremetrology/inspection/review tools that performmetrology/inspection/review processes on wafers, for example, wafersprocessed by wafer processing system 500 (it should be understood thatone metrology/inspection/review cell may receive wafers processed byseveral wafer processing systems, and that wafers may be processed bymetrology/inspection/review tools in several inspection/reviewcells)—the metrology/inspection/review tools measure and test wafercharacteristics and wafer defects, and in general,metrology/inspection/review tools may include any form of instrument,equipment, or process (either in combination or individually) thatmeasures, for example, and without limitation, dimensions of structureson a wafer, or facilitates identification of defects on a wafer ordefects in an IC formed on the wafer (generally referred to herein asdefects or wafer defects interchangeably); and (b) tool controller 1200is different from tool controller 200. Like tool controller 200, toolcontroller 1200: (a) is connected to each of the above-described systemcomponents, in a manner that is well understood by those of ordinaryskill in the art, to provide data and instructions thereto, and toreceive data therefrom; (b) controls functions performed by waferprocessing system 500, and the order in which these functions areperformed; and (c) with respect to process cells 1103-1105, at least aportion of the data and instructions provided thereto includesinformation that is referred to herein as “process recipe information”or process recipes or recipes (as is well known to those of ordinaryskill in the art, a process recipe specifies, among other things,timing, duration, and sequences of events that take place in a processcell). However, unlike tool controller 200, and in accordance with oneor more embodiments of the present invention, tool controller 1200 canmodify or change process recipes used in various ones of process cells1103-1105 in response to information received from module controllersystem 400.

[0010] In accordance with one or more embodiments of the presentinvention, module controller system 400 may utilize results produced bythe metrology/inspection/review tools to develop new recipes for use bywafer processing system 500, and other downstream wafer processingsystems. Advantageously, in accordance with one or more embodiments ofthe present invention, such modifications enable the processing resultsprovided by process cells 1103-1105 within wafer processing system 500and/or by process cells in the other downstream wafer processing systemsto be maintained within predetermined manufacturing tolerances.

[0011] It should be understood that embodiments of the present inventionare not limited to those wherein wafer processing system 500 includesmetrology/inspection/review cell 1124. In fact, further embodimentsexist wherein metrology/inspection/review tools are remote from waferprocessing system 500. Still further embodiments exist wherein analysisof results provided by the metrology/inspection/review tools are carriedout by systems other than module controller 400.

[0012] As is well known, process recipes may be transmitted to toolcontroller 1200: (a) manually from an operator using a system userinterface; or (b) automatically by means of data communication from afactory host such as, for example, and without limitation, aManufacturing Execution System (“MES”) over a communication interface(for example, a SECS/GEM port) using, for example, a well known SECStransmission protocol. In particular, such data communications typicallyare provided to tool controller 1200 through a first SECS/GEM port.SECS, the SEMI Equipment Communication Standard, enablescomputer-controlled process and metrology tools from a variety ofvendors to communicate with various types of host computers using astandard protocol in an integrated circuit (“IC”) manufacturing orfabrication facility (“fab”). Process recipe information received byinput utilizing the user interface or the first SECS/GEM port is storedat wafer processing system 500 by tool controller 1200, typically inpermanent rewritable storage such as, for example and withoutlimitation, a hard disk.

[0013] As is known, wafers are typically processed in groups that arestored in a unit that is typically referred to as a cassette (a typicalcassette holds twenty-five (25) wafers). The following identificationinformation is used to identify process recipe information stored inpermanent rewritable storage so that such information can be retrievedfor use in processing wafers in the cassette: (a) a sequence recipe IDor name (i.e., an ID that relates to the entire cassette or to eachwafer in the cassette); and (b) a process recipe ID for each processcell by which a wafer will be processed in the wafer processing system(also referred as a sequence number) in the cassette. Thisidentification information can be entered in one of two ways: (a) theoperator can define a sequence recipe ID for the entire cassette or foreach wafer in the cassette (a material ID or lot ID (“MID”) isassociated with the entire cassette of wafers—this is sometimes alsoreferred to as a cassette ID); and (b) the factory host, using the firstSECS/GEM port, can define the sequence recipe for the entire cassette orfor each wafer (an MID is associated with the entire cassette). Forexample, assume that wafer processing system includes process cells Athrough E. Then, a sequence recipe for wafer 1 might specify that wafer1 proceed first through process cell E, next through process cell A, andfinally through process cell C. As a result, the following informationmay be specified for the i^(th) wafer in the cassette: (a) MID or lotIDfor the cassette; (b) the sequence recipe ID for the cassette; (c); thenumber of process cells used to process the i^(th) wafer in waferprocessing system 1000; and (d) a process recipe name for each processcell for the i^(th) wafer (for example: (i) process cell A recipe name,(ii) process cell B recipe name, and so forth). In accordance with oneor more embodiments of the present invention, the above-describedidentification information is tracked on a wafer by wafer basis becauseeach wafer may be assigned a different sequence recipe, and more thatone sequence recipe can utilize the same process recipe in differentprocess cells.

[0014] In accordance with one or more embodiments of the presentinvention, module controller system 400 makes modifications or changesto the process recipes stored at wafer processing system 500. To do so,tool controller 1200 requests (i.e. demands) temporary process recipechanges from module controller system 400 before processing a wafer. Inresponse, tool controller 1200 receives any modification informationsent by module controller system 400 at a second communication interface(for, example, a second SECS/GEM port). The process recipe informationreceived utilizing the second SECS/GEM port, i.e., information receivedfrom module controller system 400, is then stored in memory (i.e.,temporary or volatile memory) for subsequent use. In accordance with oneor more such embodiments, modification process recipe informationreceived from module controller system 400 does not get written back topermanent rewritable storage. In this way, after processing is complete,the original or “baseline” process recipe information entered by theoperator or the factory host is maintained without having been alteredby temporary changes provided by module controller system 400.Advantageously, this enables the operator or the factory host tomaintain track of recipes s/he or it sent to tool controller 1200. Inessence, this maintains the recipes as the “customer” (i.e., theoperator or the factory host) created them.

[0015] The following describes a method by which process recipeinformation is obtained for use by tool controller 1200.

[0016] Whenever wafers are to be processed utilizing wafer processingsystem 500, a group of wafers in a cassette is placed in cassetteloadlock 1123 of factory interface 1122. Next, a cassette ID (alsoreferred to as a lot ID or MID) is transmitted to tool controller 1200.This occurs: (a) by receiving operator input through the system userinterface; (b) by receiving input from the factory host using the firstSECS/GEM port; or (c) automatically by a cassette ID reader in factoryinterface 1122 (for example, and without limitation, a barcode reader).Next, whenever a wafer is retrieved from the cassette for transfer intothe transfer chamber, a sequence number (for example, the slot number ofthe wafer in the cassette) is transmitted to the tool controller 1200from factory interface 1122.

[0017] Next, in accordance with one or more embodiments of the presentinvention, in order to process the wafer, tool controller 1200 (by meansof process cell task logic contained therein) accesses the permanentrewritable storage on a wafer by wafer basis. To do this for the i^(th)wafer in the cassette, tool controller 1200 uses the sequence recipe andprocess recipe name information for that sequence recipe as keys toretrieve a process recipe for each process cell in the sequence recipefor i^(th) wafer (the process recipe retrieved is nominal or baselineprocess recipe information for use in processing the wafer). Toolcontroller 1200 then stores the retrieved process recipe information ina data structure for use during processing. Next, tool controller 1200sends a message to module controller 400 utilizing the second SECS/GEMport to request any process recipe modification or change informationfor the i^(th) wafer, which message identifies the wafer by lot ID,sequence recipe, and sequence number in the cassette. Next, modulecontroller system 400 sends any process recipe modification informationto tool controller 1200 utilizing the second SECS/GEM port. For example,in accordance with one embodiment, module controller 400 sends allchanges that need to be temporarily applied to the process recipe for agiven process cell, and tool controller 1200 will keep this informationin a structure, for example, a lookup table, that describes all theprocess recipe parameters that need to be temporarily changed for agiven process cell. Next, tool controller 1200 writes the modificationsor changes over the nominal or baseline process recipe informationstored in the data structure in memory. For example, in accordance withone or more such embodiments of the present invention, tool controller1200 reviews the modifications, on a step by step basis, and applies themodifications by overwriting existing information in the data structurein memory. Next, tool controller 1200 directs wafer transfer system 1121to transfer the wafer to the appropriate one of process cells 1103-1105in accordance with the sequence recipe for the i^(th) wafer in thecassette. Next, tool controller 1200, utilizing the process recipeinformation stored in the data structure in memory for the wafer, sendsdata and instructions to the particular one of process cells 1103-1105to process the particular wafer. Next, after processing by one ofprocess cells 1103-1105, the wafer may be transferred to another one ofprocess cells 1103-1105 for further processing in accordance with thesequence recipe for the i^(th) wafer. As is known, some wafers may beretrieved from the cassette before processing is complete on otherwafers (for example, in a wafer processing system that includes multipleprocess cells). Further, information relating to changes for some wafersmay be retrieved while other wafers are being processed.

[0018] In accordance with one or more embodiments of the presentinvention, temporary process recipe modification or change informationmay be provided to tool controller 1200 on a step by step or processrecipe basis. For example, in accordance with one or more suchembodiments, such information is provided from module controller 400 inan XML stream that identifies the various steps of the process recipeinformation that are to be changed. In accordance with one or more suchembodiments of the present invention, the temporary process recipechange information provided by module controller system 400 includes:(a) process cell index or ID; (b) process recipe step number; (c)process recipe step parameter name (for example, a pointer to an ASCIIstring) representing a name of a process recipe step parameter; (d)parameter value (a pointer to a 32-bit integer) representing a newprocess recipe step parameter value; and (e) recipe name (an ASCIIstring that is the process recipe name for the given process cell).

[0019] In accordance with one or more alternative embodiments of thepresent invention, whenever module controller system 400 wishes toprovide temporary recipe change information to tool controller 1200,module controller system 400 transmits the temporary recipe changeinformation over the second SECS/GEM port. In response, tool controller1200 sets a system constant referred to as “EC” that is related to aparticular process cell to a non-zero number, and stores the temporaryprocess recipe change information transmitted in memory. Next, processcell task logic in tool controller 1200 retrieves process recipeinformation from the permanent rewritable storage. Next, before startingwafer processing for the process cell, the process cell task logicchecks the current value of EC. If EC is zero, there is no temporaryrecipe change information available, and wafer processing can begin.However, if EC is non-zero, the process cell task logic checks formodule controller supplied temporary process recipe change information,and writes the information into the data structure.

[0020] Advantageously, in accordance with one or more embodiments of thepresent invention, module controller system 400 may provide recipeadjustments to individual process cell tasks.

[0021] Those skilled in the art will recognize that the foregoingdescription has been presented for the sake of illustration anddescription only. As such, it is not intended to be exhaustive or tolimit the invention to the precise form disclosed. For example, the termwafer or substrate used above is used in the broadest sense, and assuch, includes wafers or substrates fabricated from all kind ofmaterials such as, for example, and without limitation, semiconductormaterials such as, for example, and without limitation, silicon, andwafers or substrates formed of a glass.

What is claimed is:
 1. A method for modifying process recipe informationutilized by a wafer processing system having a controller with permanentrewritable storage, memory, a first and a second communicationinterface, and a user interface; and one or more process cells toprocess a wafer; which method comprises steps of: storing baselineprocess recipe information in permanent rewritable storage; retrievingbaseline process recipe information from permanent rewritable storageand storing it in memory for a wafer in a group of wafers to beprocessed; receiving process recipe modification information utilizingthe second communication interface and storing the process recipemodification information in memory; overwriting at least portions of thebaseline recipe information in memory with the process recipemodification information to form new recipe information; and processingthe wafer utilizing the new recipe information.
 2. The method of claim 1which further comprises steps of: receiving the baseline process recipeinformation utilizing the user interface or the first communicationinterface.
 3. The method of claim 2 which further comprises, prior toretrieving the baseline process recipe information: identifying thegroup of wafers to be processed; identifying a wafer in the group;identifying process recipe information for the group, and identifyingprocess recipe information for each process cell in the wafer processingsystem to be used to process the wafer.
 4. The method of claim 3 whereinthe step of identifying process recipe information for the groupcomprises receiving information utilizing the user interface or thefirst communication interface.
 5. The method of claim 3 wherein theprocess recipe modification information is provided on a step by stepbasis for a process cell.
 6. The method of claim 1 wherein the processrecipe information is received in an XML stream.
 7. The method of claim3 wherein the process recipe modification information includes: (a)process cell index or ID; (b) process recipe step number; (c) processrecipe step parameter name; (d) parameter value; and (e) process recipename.
 8. The method of claim 1 wherein the controller receives processrecipe modification information and sets an indicator that suchinformation has been received.
 9. The method of claim 1 wherein the stepof receiving process recipe modification information comprises receivingfrom a controller system that transmits process recipe modificationinformation to a multiplicity of wafer processing systems.
 10. Themethod of claim 1 wherein the step of receiving process recipemodification information further comprises first requesting the processrecipe modification utilizing the second communication interface.